Nucleotide excision repair defect influences lethality and mutagenicity induced by Me-lex, a sequence-selective N3-adenine methylating agent in the absence of base excision repair
Nucleotide excision repair defect influences lethality and mutagenicity induced by Me-lex, a sequence-selective N3-adenine methylating agent in the absence of base excision repair
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DOI：
10.1021/bi035968x
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发表时间：
2004-05-18
期刊：
影响因子：
2.9
通讯作者：
Fronza, G
中科院分区：
文献类型：
--
作者：
Monti, P;Iannone, R;Fronza, G
利用酵母穿梭载体系统，我们已经报道了Me-Lex，{1-methyl-4-[1-methyl-4-[3-(methoxysulfonyl)propanamido]pyrrole-2-carboxamido]pyrrole-2-carboxamido}propane，的毒性和诱变性，Me-Lex是一种选择性地产生3-甲基腺嘌呤(3-MeA)的化合物。我们观察到，Mag1基因缺陷的突变菌株对Me-Lex的毒性比野生型更敏感，但突变性仅略有增加。Mag1是一种糖基基酶，在碱基切除修复(BER)的初始步骤中切除3-MeA以产生碱性位点。AP内切酶活性缺陷的菌株(Deltaapn1apn2)也是BER功能所必需的，它对毒性的敏感性与DelTamag1突变体相同，但突变频率显著高于DelTamag1突变体。在目前的工作中，我们探索了核苷酸切除修复(NER)在Me-Lex诱导的毒性和诱变性中的作用，因为已知NER作用于体内酵母和体外实验中的基本位点。为了做到这一点，我们删除了酵母中对NER必不可少的基因之一，即RAD14，在其他DNA修复熟练的菌株(Deltarad14)和缺乏MAGI基因的BER缺陷等基因衍生物(DelTamag1rad14)的背景下。有趣的是，RAD14的简单缺失使患者对Me-Lex的治疗不敏感。然而，当细胞同时缺乏Rad14和Mag1时，毒性和诱变性显著增强。Me-Lex在DelTamag1rad14株中诱导的突变谱与Deltaapn1/Deltaapn2或DelTamag1株中观察到的突变谱难以区分。结果表明，在酵母中，NER对3-MeA介导的毒性和致突变性具有保护作用；然而，NER的作用仅在BER缺陷背景下可察觉。
Using a yeast shuttle vector system, we have previously reported on the toxicity and mutagenicity of Me-lex, {1-methyl-4-[1-methyl-4-[3-(methoxysulfonyl)propanamido]pyrrole-2-carboxamido]pyrrole-2-carboxamido}propane, a compound that selectively generates 3-methyladenine (3-MeA). We observed that a mutant strain defective in Mag1, the glycosylase that excises 3-MeA in the initial step of base excision repair (BER) to generate an abasic site, is significantly more sensitive to the toxicity of Me-lex with respect to wild type but shows only a marginal increase in mutagenicity. A strain defective in AP endonuclease activity (Deltaapn1apn2), also required for functional BER, is equally sensitive to the toxicity as the Deltamag1 mutant but showed a significantly higher mutation frequency. In the present work, we have explored the role of nucleotide excision repair (NER) in Me-lex-induced toxicity and mutagenicity since it is known that NER acts on abasic sites in vivo in yeast and in vitro assays. To accomplish this, we have deleted one of the genes essential for NER in yeast, namely, RAD14, both in the context of an otherwise DNA repair-proficient strain (Deltarad14) and in a BER-defective isogenic derivative lacking the MAGI gene (Deltamag1rad14). Interestingly, no sensitivity to the treatment with Me-lex was conferred by the simple deletion of RAD14. However, a significant enhancement in toxicity and mutagenicity was observed when cells lacked both Rad14 and Mag1. The mutation spectrum induced by Me-lex in the Deltamag1rad14 strain is indistinguishable from that observed in the Deltaapn1/Deltaapn2 or in the Deltamag1 strains. The results indicate that in yeast NER can play a protective role against 3-MeA-mediated toxicity and mutagenicity; however, the role of NER is appreciable only in a BER-defective background.